[rrd-users] Re: MRTG & RRDTool

M.E. m.eldesoky at tedata.net
Mon Mar 17 12:53:03 MET 2003

Thanks alot Adam for the reply.
Well, I am using cacti ( http://www.raxnet.net ) as my frontend.
So it is hard to implement that method.
Plus, I have many targets (100+) that are changing alot (dynamic list of 
If I use the specified method, imagine this scenario with me.
january : I have 110 targets, I graph the total for those 110 devices.
Feb: I have 105 targets, I need to graph the total of those 105, and preserve 
the total of the 110 that was graphed in february.
Actually I tried to get the totals manually through a script and update an rrd 
file with it, but it gave me really strange results.
I have posted that problem here before, and I still have the script that did 
it, if you want to have a look.

I think the best solution now is to let mrtg (my collector) sum the tragets 
and give me the final result, but it fails when it encounters a 
non-responding device.

Any idea ??

M. Eldesoky

On Sunday 16 March 2003 7:09 pm, Adam Denenberg wrote:
> I actually had a very similar problem where I wanted to add a few targets,
> but if one target (node) was down, then one of my values was UNDEF which
> resulted in the whole thing being NaN.
> One solution is to first find out if they are UNDEF first, and then assign
> a value of 0 to UNDEFs and then add them
> DEF:A=/home/rrd/test1.rrd:ds0:AVERAGE
> DEF:B=/home/rrd/test1.rrd:ds1:AVERAGE
> CDEF:Nodes=A,UN,0,A,IF,B,UN,0,A,IF,+
>  This will turn the UNDEF values into 0 allowing you to get a result if one
> or more of the values are UNDEF, and not give you NaN.

> Adam
> On 3/16/03 6:22 AM, "Mohamed Eldesoky" <m.eldesoky at tedata.net> wrote:
> > Hello
> > I want to run mrtg so that it sums the values from multiple targets.
> > MRTG uses rrdtool.
> > If for some reason, one device is not responding, the whole process stops
> > !! I think it is something related to NaN phenomena.
> > Anyone faced something like that ??
> > Any work around ??

Person who say it cannot be done should not interrupt person doing it.  
--Chinese Proverb 

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